Early Journal Content on JSTOR, Free to Anyone in the World This article is one of nearly 500,000 scholarly works digitized and made freely available to everyone in the world by JSTOR. Known as the Early Journal Content, this set of works include research articles, news, letters, and other writings published in more than 200 of the oldest leading academic journals. The works date from the mid-seventeenth to the early twentieth centuries. We encourage people to read and share the Early Journal Content openly and to tell others that this resource exists. People may post this content online or redistribute in any way for non-commercial purposes. Read more about Early Journal Content at http://about.jstor.org/participate-jstor/individuals/early- journal-content . JSTOR is a digital library of academic journals, books, and primary source objects. JSTOR helps people discover, use, and build upon a wide range of content through a powerful research and teaching platform, and preserves this content for future generations. JSTOR is part of ITHAKA, a not-for-profit organization that also includes Ithaka S+R and Portico. For more information about JSTOR, please contact email@example.com. MYCOLOGIA Vol. X November, 191 8 No. 6 DALDINIA VERNICOSA— A PYROXY- LOPHILOUS FUNGUS Arthur S. Rhoads (With Plate 14) The collector is thoroughly aware that numerous species of fungi occur prevailingly on burnt places. Although some of these forms are found elsewhere occasionally, many are so constantly associated with burnt places that they are sought only in such a habitat. In order to account for this peculiar association many plausible but inadequate reasons have been advanced. The fact remains, as stated by Seaver (i), that sterilization of the sub- stratum by heat apparently brings about some change in the soil other than the simple elimination of competition in the destruc- tion of bacteria and other fungi, which changes appear to be of vital importance in the cultivation of fungi which normally grow on a burnt substratum. Later experiments by Seaver and Clark (2), dealing with the artificial cultivation of a species of Pyro- nema, show that soil heated in various ways, especially by burning over the surface, becomes a very favorable nutrient medium for fungi of various kinds by reason of the large amount of food ma- terial rendered available through the heating of the materials in the soil. It is only natural to suppose that wood or bark, when burnt, likewise becomes a more favorable medium for the growth of certain fungi. The writer has made several collections of Daldinia vernicosa (Schw.) Ces. & De Not. in various states throughout the East and generally finds it to be associated with fire-scorched trees. So far [Mycologia for September (10: 231-275) was issued September 25, 1918.] 277 278 Mycologia as can be determined this fungus is confined entirely to dicotyle- donous trees but occurs upon a great number of species, prefer- ably upon fire-scorched trunks. It attacks small saplings even more readily than larger trees and seems to prefer species of hickory for a host. While making a survey of a burned area in the latter part of August, 19 16, with a view to securing data in regard to the rapidity of the deterioration of standing fire-killed timber by one of our most common sap-rotting fungi, the writer was impressed by the abundance of Daldinia vernicosa on the dead trees. An area was selected near State College, Pa., that had been burned for the first time, a surface fire having swept through it 1 year and 3 months previously. As a result the trees on this area, with few exceptions, were scorched so badly that they were killed out- right. From this burned area an average sample tract, 100 by 500 feet, was laid off and the following data were secured for each standing tree within this tract: species, diameter (measured to the nearest inch) at breast height, conditions (as to whether dead or living), and the species of fungi growing upon it as evidenced by the sporophores upon the trunk. The species of trees upon this tract in the order of their importance were white oak, scarlet oak, white pine, mocker nut hickory, red maple, chestnut, and pitch pine. The data obtained are given below, the trees being tabulated by diameter under each species : Out of 71 scarlet oak trees upon this tract only 1 bore sporo- phores of Daldinia vernicosa. There also were present 15 red maples, 6 chestnuts, 2>7 white pines, and 1 pitch pine but no trees of these species bore sporophores. Out of a total of 363 dicotyle- donous trees occurring upon this tract 46, or 13 per cent., bore sporophores of Daldinia vernicosa within 1 year and 3 months after the trees were scorched by fire. All the trees tabulated above, save one, were dead at the time of the reconnaissance. The above figures clearly indicate how extensively and rapidly this ascomycete can propagate itself when afforded a favorable substratum. The accompanying photograph (Plate 14, A), taken in the latter part of August with a previous record of two months of dry weather, testifies to the luxuriant growth made by the Rhoads: Daldinia vernicosa 279 Summary of Trees Bearing Sporophores of Daldinia vernicosa by Species and Size Species 1 D.B.H. inches! No. of trees on | area No. bearing sporophores of D. vernicosa Per cent bear- ing sporophores of D. vernicosa QtitTCus alba 2 3 4 5 6 7 8 9 10 1 1 12 5i 37 40 33 27 19 8 3 6 3 16 5 5 6 1 25 31 14 12 << «t .1 ti < t 18 << 4 »< 1 1 .. << tt ti Quercus alba, total trees 236 36 15 Hicoria alba I 2 3 4 5 6 7 7 12 6 5 3 1 1 2 4 2 1 29 33 33 ti «. ti tt ., it tt 100 ' 1 Hicoria alba, total trees 35 9 26 sporophores of this fungus. Sporophores gathered and taken into the laboratory at this time shed copious quantities of spores. Associated with Daldinia vernicosa was another pyrenomycete, Nummitlaria Bulliardi Tul. The stroma of this fungus is effused, thin, and crustaceous. It overspreads the surface of the inner bark, throwing off the epidermis for 6 inches or more in extent and is black and carbonaceous at maturity. This fungus, how- ever, was found only on the white oak and scarlet oak trees. It is quite common throughout this region but always associated with dead oak trees. It is not, however, so restricted to fire-killed trees as is its associate, Daldinia vernicosa, but is apparently always associated with dead trees, preferably oak trees. The genus Daldinia is characterized by the peculiar structure of the stroma, which is superficial, subglobose, and has a black and carbonaceous external layer when mature, in which the perithecia are imbedded. The stroma is softer inside, of a radiate-fibrous structure and concentrically zoned. There are 24 species of Daldinia, mostly from the tropics, given 280 Mycologia in Saccardo. For the most part they can be referred to Daldinia concentrica, which is a common and widely distributed plant oc- curring in almost every country in the world. In Australia this species assumes large size, frequently becoming two or three inches in diameter as it sometimes does in the western United States. In Europe, Daldinia durissima was proposed by Fries many years ago, but, according to Lloyd (3), no one else ever found it, a type at Kew being only the common D. concentrica. Massee found a specimen in tropical America (Trinidad) which he named Daldinia aspera. Lloyd, however, states that this spec- imen is not a Daldinia (3) at all but a Hypoxylon, probably H. cerebrinum (4). Leveille discovered two species in the United States, D. cingulata and D. loculata, but Lloyd (3) states that both are the common D. concentrica. Two well-known and ap- parently distinct species of Daldinia occur within the United States, namely D. concentrica (Bolt.) Ces. & De Not. and D. ver- nicosa (Schw.) Ces. & De Not. Peck (5), in his list of the plants of North Elba, reports Dal- dinia vernicosa on dead trunks of young, standing deciduous trees. He states that it is very doubtful if this and D. concentrica are really distinct species, and is of the opinion that connecting forms occur. It would appear that Peck had not collected Daldinia ver- nicosa as typified by the specimens in the Schweinitzian her- barium, for, if he had done so, it is difficult to see how such speci- mens could be considered identical with D. concentrica. The stroma of Daldinia concentrica is subglobose or hem- ispheric, or rarely obovoid, while that of D. vernicosa is sub- turbinate and sometimes contracted behind into a thick stipe-like base which is often concentrically wrinkled. The stromata of both species become black when mature, but that of D. vernicosa becomes distinctly shining. When young and immature the stroma of D. vernicosa contains a large quantity of a colorless gelatinous substance which dries down at maturity, forming the radiate-fibrous substance between the concentric zones. At ma- turity practically all of the substance between the thin, blackish, concentric zones under the terminal, monostichous perithecial layer is made up of a colorless, radiate-fibrous, dry-gelatinous Rhoads: Daldinia vernicosa 2&1 substance. It is thus seen that the interior of the stroma of this plant is of a very heterogeneous texture. As a result of the loose texture of the radiate-fibrous inner substance the mature fruit- bodies can be crushed readily between the fingers. In Daldinia concentrica the interior of the stroma also is of a radiate-fibrous structure. Owing to its more homogeneous structure, however, it is fairly firm and solid, and specimens that have not been attacked by insects are very resistant to crushing. In the latter plant the radiate-fibrous substance is brown instead of colorless, as it is in d & CO Fig. i. Spores of Daldinia vernicosa showing various stages in the dehis- cence of the exospore wall after treatment with dilute KOH ; a, spore at time of shedding; b, spore showing the initial step in the dehiscence of the exo- spore wall ; c and d, spores showing the casting off of the exospore membrane ; e, cast-off exospore membranes, some with the valves still hinged together; /, a later stage of e, showing the return of the two valves to their original posi- tion. X 500. D. vernicosa (Plate 14, B), and the concentric zones are not so sharply defined as those of the latter species. As pointed out by Ellis and Everhart (6) the perithecia of D. concentrica are monostichous and not polystichous as stated by Saccardo. But little difference is exhibited by either the perithecia, asci, or spores of the respective species. The spores of D. concentrica are ob- liquely uniseriate with the ascus, inequilaterally elliptical, dark- brown, and finally opaque. They are somewhat variable in size but usually conform to 12. 5-18 n by 7-10 /x. The spores of D. vernicosa are about the same size as in the preceding species but are somewhat smaller and less variable in size. They usually con- form to the limits of 1 0-14.5 //, by 7-7.5 /*. 282 Mycologia The spores of Daldinia vernicosa are peculiar in that, when mounted in dilute (5 per cent.) KOH or NaOH, the exospore wall, which is colorless, quickly dehisces and separates from the spore, which is dark-brown. A single peripheral line of dehiscence occurs at the center of the spore and the two halves of the exo- spore wall usually break away from one another as two valves, or they may dehisce partially and bend backward as if they were hinged, thus allowing the spore to free itself from its peripheral membrane (Fig. 1). The spores of Daldinia concentrica also ex- hibit the same behavior, and, with equal facility. These obser- vations on the dehiscence and shedding of the colorless exo- spore wall of these two species, when the spores have been mounted in dilute solutions of KOH and NaOH as well as certain other dilute alkaline solutions, have been confirmed by the careful and repeated examination of specimens from widely distant points in several localities. This dehiscence of the exospore wall is less evident, however, in old herbarium material. Ellis and Everhart (6) sum up the differences between Dal- dinia vernicosa and D. concentrica as follows: "This (D. verni- cosa) is distinguished from D. concentrica by its shining-black stroma, and the looser texture of the radiate-fibrous inner sub- stance which is cut by 8-12 dark-colored, membranaceous hori- zontal plates or layers. These are very noticeable in a vertical section even in the young plant, while it is still covered with the conidial layer and before the terminal, subglobose, ascigerous stroma has begun to appear. In the mature state, the fibrous inner substance and the horizontal membranes disappear to a greater or less extent, and leave the stroma more or less hollow, so that it may be easily crushed with the fingers, but in D. concentrica the inner substance remains firm and is also of a darker color. " Daldinia concentrica, according to Lindau (7), is of cosmo- politan occurrence on dicotyledonous wood, while D. vernicosa, according to Saccardo (8), is less widespread in its distribution. In addition, the latter species generally occurs on burned woody stems, whereas the former species does not seem to be pyroxylo- philous. It is often very difficult to secure mature specimens of D. con- Rhoads: Daldinia vernicosa 283 centrica, and sometimes exceedingly difficult to secure mature specimens of D. vernicosa that are free from insects. Even after excellent specimens are collected, the interior portions of the stroma usually are eaten out by the larvae that hatch out within the specimens, unless they are quickly oven-dried. In addition to his own collections the writer has examined spec- imens of both plants in the herbaria of Dr. L. O. Overholts, The Pennsylvania State College, The New York State College of For- estry, Office of Pathological Collections in the U. S. Bureau of Plant Industry, the Schweinitzian herbarium in the Academy of Natural Sciences at Philadelphia, and the collections of the Office of Investigations in Forest Pathology. The Schweinitzian her- barium contains the type specimens of Daldinia vernicosa, which were first described as Sphaeria vernicosa by Schweinitz from specimens collected at Salem, North Carolina. Summary i. Daldinia vernicosa, as is typical of certain other fungi, oc- curs prevailingly on a substratum of burnt wood, and is to be re- garded as a pyroxylophilous fungus. 2. In its occurrence, it apparently is confined to dicotyledonous species and attacks fire-killed saplings, particularly those of hick- ory, with great vigor. 3. Out of a total of 363 dicotyledonous trees occurring upon an average sample tract ( 100 by 500 feet) of a burned area, 46, or 13 per cent., bore sporophores of Daldinia vernicosa within 1 year and 3 months after the trees were scorched by fire. 4. Of the 24 (mostly tropical) species of Daldinia given in Sac- cardo, most of them can be considered as mere growth forms or ecological expressions of Daldinia concentrica, a widely distributed plant of cosmopolitan occurrence. 5. Only two species of Daldinia occur in the United States, D. concentrica and D. vernicosa, which appear to be morphologically quite distinct. 6. The dehiscence, of the colorless exospore wall occurs along a single central peripheral line and seems to be a characteristic feature of regular occurrence with the spores of both Daldinia 284 Mycologia vernicosa and D. concentrica, when mounted in dilute alkaline solutions. Office of Investigations in Forest Pathology, Bureau of Plant Industry, Washington, D. C. Bibliography i. Seaver, Fred J. Studies in pyrophilous fungi — I. The occurrence and cultivation of Pyronema. Mycologia i: 131--139. pis. 9-12. 1909. 2. Seaver, Fred J., and Clark, Ernest D. Studies in pyrophilous fungi — II. Changes brought about by the heating of soils and their relation to the growth of Pyronema and other fungi. Mycologia 2: 109-124. pis. 24-26. 19 10. 3. Lloyd, C. G. Daldinia vernicosa. In Mycological notes. No. 43, p. 604. 1916. 4. Lloyd, C. G. Hypoxylon cerebrinum. In Mycological notes. No. 42, p. 579. 1916. 5. Peck, C. H. Plants of North Elba, Essex Co., N. Y. New York State Museum Bui. 6: 67-266. 1899. (See p. 229.) 6. Ellis, J. B., and Everhart, B. M. Daldinia vernicosa. In The North American Pyrenomycetes, p. 661. 1892. 7. Lindau, G. Daldinia DeNot. In Engler and Prantl's Die natiirlichen Pflanzenfamilien. Teil I, Abteilung I, p. 487. 1897. 8. Saccardo, P. A. Daldinia vernicosa. In Sylloge. Vol. i, p. 394. 1882. Explanation of Plate 14 A. Trunk of white oak (Quercus alba L.) one year and three months after it was killed by a light surface fire, showing the abundance of Dalidinia verni- cosa. The trunk bears a 6-inch rule. B. Sporophores of Daldinia vernicosa, showing both external and sectional views, natural size. Mycologia Volume io, Plate 14 A B DALDINIA VERNICOSA (Schw.) Ces. and De Not.